Mysterious loss of power

Hi,
I have recently purchased a 2LT 76 Bay camper (auto) with 170k on the clock. It has a fault that i have not been able to identify which is becoming quite frustrating considering i have spent over 2k on the mechanical,s so far.
This is how it goes:
The engine starts and runs perfectly every time, then after about about 15 to 20km there is a significant loss of power. Feels like its restricted. It will loose power until it eventually comes to a stop, but still remains idling. After a period of time, sometimes 5mins is enough, it will start up and carry on as if nothing has happened, then repeat the process 15min later.
I have explained the drama with a reliable VW mechanic but he has not yet experienced the problem first hand, so has not been able to identify it. Murphy s law is it wont play up whilst he's in it.
It's driving me nuts! can anyone PLEASE help.
Cheers and safe motoring!

have you checked to make sure its not clogged fuel lines ????

Thanks! I had a feeling that there may have been a fuel issue, so my mech rebuilt and pressure tested the fuel pump, and replaced the filter. I think I'll drain the tank and check the lines anyway. Cheers.

it could be the accelerator pump on the carby...
if it doesn't work the car can idle all day....

but You cannot drive it...
You need that extra fuel to take off....

I had two carbies that had the accelerator pump valve blocked with old fuel....
You can't access the valve...

but the engine would start and idle all day...
but I couldn't drive it onto the road... lol

LEE

http://community.webshots.com/user/vw68autobug

Sounds like a classsic case of fuel starvation,possibly a worn fuel pump pushrod or a blocked outlet in the tank.Check the fuel flow first and then the pushrod length 140mm. The othe possibility is a fuel line running past the heater box or sitting on the crankcase causing vapourisation

two things I can think of it might be
1.check and replace fuel filter
2.Check the fuel tank is vented

silver wrote:two things I can think of it might be
1.check and replace fuel filter
2.Check the fuel tank is vented

How do you make sure the fuel tank is vented?

I've seen a few rusty fuel tanks that cause exactly what you are saying...... the flakes of rust block the pickup in the tank. Trying to prove it could be expensive for you if you cant do the work yourself though. Either the motor has to come out to get at the tank, or cut a hole in the floor above the fuel tank so you can remove the fuel sender to have a look inside.

Umm, mabe try taking the fuel cap off and go for a drive, instead of cutting a hole for ventilation?
Or i think pushrod length, as this is what happened to me, commonly missed.